The extraction process has been used for centuries for the isolation of desirable materials. The process involves the mixing of a solvent with extractable material, separation of the solution that is formed, and removal of the solvent from the solute, a desired material.
U.S. Pat. No. 5,512,285, to Wilde, teaches a batch process for extraction of organic components from plant material. The process uses tetrafluoroethane as the extraction solvent. The process allows extraction of some desired components at near ambient temperatures, and is economical relative to super critical CO2 extractions at high pressure. The system uses a tumbler to mix solvent and plant material in a sealed extractor, which is connected to an evaporator that is warmed in an immersion bath with a heater, the evaporator is connected to a compressor to effectively remove and retain the majority of the expensive solvent and return it to the extractor, if needed. The evaporator was the receiver for the extract, which when the evaporator dropped in pressure to zero psig the evaporator was opened and the extract drained from the evaporator. The evaporator is then connected to the compressor and heated to recover virtually all the solvent.
Hence, a flexible system permitting extraction that retains solvent nearly quantitatively, is cost effective, energy efficient, and can permit an effectively continuous operation is desirable.